In this project, we’re going to design a single transistor FM transmitter circuit that works efficaciously in a 1-2 km variety. On this circuit, we have used an electret condenser microphone as entering supply that advantage sign in analog form. You may without problems make this transmitter on PCB or without PCB as it consists of very few components. The coils and the antenna may be designed as part of the PCB as an antenna if you make it on PCB. If you need to increase the variety of the transmitter then you definitely have to set up the long excessive antenna with any cord. To apprehend the running of this transmitter we divide it into 3 important levels s as follows

Single transistor FM transmitter

Input degree

Modulation degree

Output stage

1. Enter level nation Of FM Transmitter

Enter degree includes Capacitors C1 and C3, and resistor R1 and microphone. Input signals into the FM transmitter should not incorporate a DC aspect as it’d negative have an effect on the modulation stage and therefore no FM sign would be generated therefore C3 capacitor is used to govern the DC destructive. Resistor R1 (resistor) presents a small amount of contemporary to the base of the transistor so in this way transistor stays on and 1st stage complete in this way.

2.Modulation level

The oscillator/modulation degree includes C2(variable capacitor for adjusting frequency), C4, L1, and R2 with the frequency of oscillation being decided with the aid of C2 and L1 simplest. The modulation stage provides a service sign that is modulated by using the enter indicators remember that enter indicators are received via the microphone or any enter supply. While we deliver energy to the circuit a rush of current flows through the L1 (inductor). This current passes through the capacitor C4 and because of this cutting-edge go with the flow via R2. R2 is connected with the emitter of the transistor so the identical voltage present on the emitter. As voltage growth on the emitter, reduces In VBA reduces the condition of the transistor. Whilst strength is applied to the circuit, a hurry of modern flows through the inductor.

This rush of current can even pass-thru C4 via capacitive coupling if you want to bring about present-day flowing through R2. Contemporary flowing via R2 will result in a voltage drop throughout R2 and since R2 is hooked up to the emitter of Q1, the identical voltage could be a gift at the emitter of Q1. As C4 starts to feed the small amount of modern-day go with the flow via C4 reduces and in this way much less present-day bypass through R2 due to this size of VBA increase and conduction will increase. Due to growth in conduction c4 discharging and complete cycle begin to repeat again.

3. Output/Emitting stage

The alerts which might be generated by way of modulation level are emitting via a long cord (antenna). A way to receive Fm transmitter signals The Fm Transmitter signals may be received via FM receiver along with simple FM radio and inside the gift age ordinarily, the cellphone has also the feature of FM receiver. The unmarried transistor FM transmitter frequency can be searched through the FM receiver among 88MH. This frequency may be modified with the variable capacitor or expands the jewelry of inductor coil L1. Fm transmitter frequency should be adjusted on an empty region of looking in any other case it’ll disturb the frequency of close to tuned radio which isn’t always allowed by law.

Single transistor FM transmitter 

It’s a very very Small FM transmitter you can make it with few additives

Components Required

  • Micro-cellphone
  • Transistor 2n2222/2655c
  • Inductor Coil five Turns With 16 No  Copper cord
  • Pf 102(100nf)
  • Pf 47
  • 100 Ohm Resistor
  • 4.7k Resistor
  • 3 To 6v Battery

Animated circuit diagram

FM Transmitter


The antenna needs to be linked with the emitter point of the transistor excessive antenna will boom the variety of transmitter

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